This invention relates to a posture control device for marine vessels and more particularly to an arrangement for controlling the trim position of a watercraft to obtain optimum watercraft conditions and also adjusting the trim condition to maintain the desired posture for the watercraft.
There have been proposed several devices for adjusting the trim of a propulsion unit for a watercraft so as to obtain optimum watercraft running conditions. For example, devices have been proposed for adjusting the trim of the propulsion device so as to maintain the watercraft hull in a planing condition. Other devices adjust the trim so as to obtain maximum acceleration, speed and/or fuel economy. Although such devices are particularly desirable, they fail to take into account the fact that the stability of the watercraft may deteriorate even though the performance of the watercraft in other regards is optimized.
One form of trim control is operative to trim the propulsion unit down fully during initial acceleration and then to gradually trim the propulsion unit up as the speed of the vessel increases. Such automatic devices are advantageous in that they do not depend upon the skill of the operator. In addition, the operator need not direct his energies and attention toward obtaining the optimum trim position in deference to other matters which require his attention. However, as the speed of the watercraft increases, the area of the hull in contact with the water will decrease and the stability of the watercraft may be reduced even though the speed or acceleration is optimized.
It is, therefore, a principal object of this invention to provide an approved arrangement for controlling the trim of a propulsion unit for a watercraft.
It is a further object of this invention to provide a watercraft propulsion unit control that will obtain optimum performance but which also is operative to maintain the desired posture of the watercraft in preference to optimum performance.
It is a still further object of this invention to provide an automatic watercraft trim control wherein trim is optimized and stability is also optimized.